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DIGITAL BREAST TOMOSYNTHESIS
(DBT)
Luc Rotenberg, Gregory Lenczner, Henri Ouazan ISHH – RPO Clinique Hartmann – Ambroise Paré
Neuilly Sur Seine - France #drrotenberg
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As a matter of fact we know:
• Breast screening target is EARLY DIAGNOSIS OF BREAST CANCER
• In most of the cases Screening reaches the
goal
• almost 10 – 15% of the found late cancers is originated in regularly screened women
• FFDM is “blind” under some particular
circumstances : • dense breasts • dense tissues overlapping lesions
FFDM: SUPERIOR TECHNIQUE, BUT NOT PERFECT
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The challenge of tomosynthesis
An efficient DBT system should accomplish some basic requirements:
• The total released dose should be lower than the one released during an FFDM exam and the closest possible to a 2-D FFDM projection • The image quality should be same as the 2-D, but it has to provide much more clinical information. • The exam has to be the shortest possible (fast scan). • The scan angle should be large enough to provide an adequate depth (3-D) resolution.
DOSE 3-D circa = DOSE 2-D
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SCAN ANGLE– PROS & CONS
Wide angle:
+ It provides superior depth resolution: ideal 360° (CT) - It causes mechanical movement complexities - It causes longer scan time
Small angle:
+ More simple design / construction mechanics + Shorter scan time - Lower Depth resolution. Loss of details perception
15° (±7,5°)
(Hologic Dimensions)
40° 50°
(GE Essential-Siemens Inspiration)
GIOTTO: 40°
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NUMBER OF PROJECTIONS PROS & CONS
Large Number:
+ Better reconstruction because more data to the 3-D algorithm
- Lower S/N per projection because the total dose is unchanged = Low Image Quality
- Longer scan time
Small Number:
- Less data for the 3-D algorithm
+ Higher S/N per projection = Improved I.Q.
+ Faster scan
• Hologic Dimensions: 15 exp. • GE Essential: 9 exp (or 15?) • Siemens Inspiration: 25 exp. • Giotto Tomo: 13 exp with variable
angles
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-20° +20°
Compression plate
Breast
Digital detector
� The tube moves rapidly along an arc stopping at each exposure for a fraction of a second
� The images are
shown as 1mm “slices” or more (slab)
Giotto:13 Projections
STEP & SHOOT
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CONTINUOUS AND STEPPING MOVEMENT: PROS & CONS
Continuous + It is faster = Faster scan time + Much simpler mechanics to design and to build
- The exposures during the tube’s movement create anyway a “blurring” effect so causing the loss of “crispy” contours of the details, especially of the
tiny microcalcifications
Step & Shoot
- More complex mechanics to avoid vibrations due to variations of speed + The images made in “frozen” conditions are clear and “crispy”. No detail is lost.
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PIXEL DIMENSION/ BINNING
Binning: Virtual combination of two or more pixels of the detector matrix. Usually 4.
+ The total number of pixel decreases 75% shortening the detector reading, decreasing the weight of the file and the 3-D recon time
- The spatial resolution decreases dramatically with loss of details that, if simultaneously the tube movement is continuous, causes an important decrease of micro calcifications visibility.
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• Non CT style, but DBT dedicated
• Low number of artifacts
• Better micro calcifications visualization • Better visualization of the skin line
• Better S/N ratio
• It requires less projections
• The projections can be further apart
ADVANCED 3-D ITERATIVE ALGORITHM
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Pooled BI-RADS–based ROC curves for diagnostic assessment of conventional diagnostic views and tomosynthesis views
Zuley M L et al. Radiology 2013;266:89-95, Pittsburgh
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DBT
ROC curves for average probability of malignancy as assessed by using conventional supplemental diagnostic views and tomosynthesis views.
Zuley M L et al. Radiology 2013;266:89-95
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Pooled ROC curves for reader studies 1 and 2 using probability of malignancy scores; curves represent average ROC performance
for 12 readers in study 1 and 15 in study 2.
Rafferty E A et al. Radiology 2013;266:104-113
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Assessing Radiologist Performance Using Combined Digital Mammography and Breast Tomosynthesis Compared with Digital Mammography Alone: Results of a Multicenter, Multireader Trial
Diagnostic Sensitivity, Specificity, and Positive and Negative Predictive Values
Rafferty E A et al. Radiology 2013;266:104-113, Boston
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Applications
1. Detection « screening » 2. Caracterisation 3. localisation
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Applications
1. Detection « screening » 2. Caracterisation 3. localisation
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Detection
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Applications
1. Detection « screening » 2. Caracterisation 3. localisation
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Mme P.
S National Screening program
S 68 y
S No history
S Clin examination normal
S P2,G2
S Menauposal, No hormonal traitment
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2D Digital Mammography
Right CC Left CC
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Right AXIL Left AXIL
2D Digital Mammography
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Localized incidences
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DBT
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Wire Marker
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43 y, screening
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43 y, screening
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43 y, screening
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43 y, screening
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Applications
1. Detection « screening » 2. Caracterisation 3. Localisation
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Breast US diagnostic & balistic
IDC grade 2, RH+, Her2 -
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US Biopsy & Wire Marking
IDC grade 2, RH+, Her2 -
Large core 16g Biopsy Wire marker
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Dose ?
Full Field Digital Mammogram + Digital Breast Tomosynthesis FFDM + DBT = dose x 2
Two-dimensional Synthesized Mammograms + DBT
2D SM + DBT = dose x 1 Hologic C-View*
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FFDM SM Margarita L. Zuley; Radiology 2014, Ahead of Print.
Comparison of Two-dimensional Synthesized Mammograms versus Original Digital Mammograms Alone and in Combination with Tomosynthesis Images
123 patients
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Margarita L. Zuley; Radiology Ahead of Print DOI: 10.1148/radiol.13131530, 2014 by the Radiological Society of North America, Inc.
Comparison of Two-dimensional Synthesized Mammograms versus Original Digital Mammograms Alone and in Combination with Tomosynthesis Images
Overall ROC curves based on probability of malignancy ratings for individual breasts. FPF = false-positive fraction, TOMO = tomosynthesis, TPF = true-positive fraction.
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Margarita L. Zuley; Radiology Ahead of Print DOI: 10.1148/radiol.13131530, 2014 by the Radiological Society of North America, Inc.
Comparison of Two-dimensional Synthesized Mammograms versus Original Digital Mammograms Alone and in Combination with Tomosynthesis Images
Overall breast-based ROC curves for forced BI-RADs ratings. FPF = false-positive finding, TOMO = tomosynthesis, TPF = true-positive finding.
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S The use of SM in lieu of FFDM, whether alone or in combination with tomosynthesis , does not result in any clinically meaningful differences in diagnostic accuracy
S Two-dimensional SM can be used as an acceptable replacement for directly acquired mammograms in tomosynthesis-based evaluations.
S The use of SM reduces radiation dose to patients undergoing tomosynthesis-based screening mammography.
Margarita L. Zuley; Radiology 2014, Ahead of Print.
Comparison of Two-dimensional Synthesized Mammograms versus Original Digital Mammograms Alone and in Combination with Tomosynthesis Images
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Two-View Digital Breast Tomosynthesis Screening with Synthetically Reconstructed Projection Images: Comparison with Digital Breast Tomosynthesis with Full-Field Digital Mammographic Images Per Skaane & all. Oslo, Norway. Radiology 2014, Ahead of Print.
S 12 270 women were compared in terms of cancer detection and false-positive rates with the reconstructed 2D images / FFDM plus DBT interpretations (2012 january-december)
S Cancer detection rates were 7.8, and 7.7 per 1000 screening examinations for FFDM plus DBT and reconstructed 2D images plus DBT.
S False-positive scores were 4.6%, and 4.5%, respectively. S Corresponding reader-adjusted paired comparisons of false-positive scores
revealed no significant differences (ratio = 0.99; 95% confidence interval: 0.88, 1.11; P = .85).
S Conclusion : combination of reconstructed 2D images and DBT performed comparably to FFDM plus DBT is adequate for routine clinical use when interpreting screening mammograms.
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Mediolateral oblique images in 61-year-old woman with 12-mm invasive lobular carcinoma in the right breast. Left: FFDM image. Middle: Current synthesized 2D image. Right: DBT image. The region of interest is magnified for each image. Reader scores for the study were 1 for FFDM, 3 for FFDM plus DBT, and 4 for synthesized 2D images plus DBT. Radiology, Skaane; Andriy I. Bandos; Ellen B. Eben; Ingvild N. Jebsen; Mona Krager; Unni Haakenaasen; Ulrika Ekseth; Mina Izadi; Solveig Hofvind; Randi Gullien; Radiology Ahead of Print DOI: 10.1148/radiol.13131391
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Conclusion Take Home Messages
S Best detection
S Best caracterisation
S Best localisation
S Dose : SM +++
S Time
S Pricing
S National Screening Program ?
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